Braun tube



Dec. 28, 1937. scHLEslNGER 2,103,645

BRAUN TUBE Filed Dec. 14, 1933 Patented Dec. 28, 1937 UNITED STATESPATENT OFFICE BRAUN TUBE Kurt Schlesinger, Berlin, Germany ApplicationDecember 14, 1933, Serial No. 702,314 In Germany December 20, 1932 3Claims. (Cl. 250-275) 10 r Z3 Z if h is the height of the image and ethe number of lines. j

, Further objects of the invention will be seen from the followingdescription.

The invention will be more fully understood from the drawing, whereinFig. 1 shows diagrammatically the basic arrangement according to theinvention, I

Fig. 2 shows by way of example aform of embodiment of the invention, 7 sFig. 3 shows a special embodient of the middle plate of the deflectingsystem, while Fig. 4 shows a diagram of thedefiecting plates connectingsystem.

Fig. 5 shows a further embodiment of a'Braun tube according to theinvention. 7 According to the invention, there is first produced abundle of cathode rays of any desired and preferably roundcross-section, which bundle is afterwards so formedby the action ofsuitably selected attraction and/or pressure fields that the imagepoints possess the desired cross-section.

The basic diagram of the arrangement according to theinvention isillustrated by way of example in Fig. 1. The preferably pre-concentratedcathode ray of desired form is conducted between two pairs of knifeedges 3|, 32 and 33, 34.

By applying suitable potentials to these knife edgesit is possible togive the rayany desired cross-section. If, for example, it is desired toimpart to the ray a rectangular form, whereby the height is greater thanthe Width, the knife edges 31 and 32 are linked up with thesame'potential, which is positive as compared with the ray, while theknife edges 33 and 34 are'furnished either with a slight positive ornegative bias as compared with the ray. By varying the potentials it ispossible to vary the cross-section of the ray as desired.

To produce a cross-section of the ray which is confined as far aspossible by straight lines, it is desirable to dispose the pairs ofknife edges in different planes.

In tube systems which contain. diaphragms themselves, and moreparticularly slot diaphragms, these diaphragms may be employed in placeof special pairs of knife edges, more particularly if the length of theslot differs consider- ,4

ably from the width thereof, so that the effect of the two remote edgesof the diaphragm may be ignored.

The use of the method according to the inven- V ti'on, employing slotdiaphragms already existing in the system, will be described inconjunction with a tube furnished with three-plate systems as isdescribed in the application Serial No. 694,915 filed October 23, 1933.V

A tube of this nature ,is shown by way of example in Fig. 2. V

In the drawing l is the neck of the tube, 2 the Wehnelt-cylinder, 3 thecathode, 4 the, first or screening anode, 5 an after-concentrationcylinder, 6 and after-acceleration anode, and i5 and. I6 are the twothree-plate systems which consist of the outer plates 8 and i0 and I!and I9 and the middle slotted plates 9 and L8. The two outer plates ofthe systems may be linked up with anode potential, while the middleplate possesses a potential which is positive in relation tothe anode.The cathode ray passing through the anode 6 at first enters the spacebetween the plates 8 and 9; is deflected through the slot 1.4 andpassesout of the system. The final direction of the non-deflected ray isparallel to its direction 7 of entry between the plates 9 and 10. Thepath of the ray is corresponding in the second system. To produce arectangular cross-section of the ray it is necessary, as set forth inthe above, to

employ two fields vertical to each other, which may be produced by theuse of vertically disposed pairs of electrodes which, for example, mayhave the shape of knife edges.

Now it is possibleto replace the pair of knife edges causing the shapingof the ray in the transverse direction, (i. e., in the directionvertical to the line, and accordingly in the longitudinal direction ofthe slot I4) by the action of the diaphragm I4. For this purpose thediaphragm must be constructed in such fashion that the attraction fieldof the plate 9, which in itself possesses a positive potential ascompared with the ray, produces the desired enlargement of the ray inthe transverse direction and does not affect the form of the ray in thelongitudinal direction.

The Width of the slot, therefore, is preferably increased, while themarginal faces of the slot situated in the direction of the axis of thetube may be approached to such extent towards the ray as is necessaryfor obtaining the effect according to the invention.

With a diameter of the pencil of rays amounting to 2 mm. a length ofslot l4 amounting to 6 mm. has been found to be suitable assuming theplate 9 possesses a potential of 200 volts as compared with the ray. Theplates furnished with the slot may be preferably constructed as crankedplates as described in the application Serial No. 694,915, filed October23, 1933. The term cranked plate means a plate having three parts, thetwo outer parts being parallel to each other and the middle part beinginclined with respect to each of said outer parts, the slot beingprovided in the inclined portion. The middle plate l8 of the secondthree-plate system I6 may conveniently be constructed in such fashionthat the slot exerts no shaping effect on the ray at all. For thispurpose, the slot, as illustrated by way of example in Fig. 3, isconstructed in such a manner that the edges of the slot are still spacedto such extent from the ray, even at the greatest possible deflection ofthe ray, that they are unable to exert any appreciable effect on thesame.

By reason of the arrangement as described it is accordingly possible insimple fashion to impart to the cross-section of the ray any desiredform in the transverse direction. Corresponding forming in the directionvertical thereto-referred to in the following as the longitudinaldirection-may be obtained by a suitably arranged pair of knife edges ofsuitable potential.

It is, however, also possible in accordance with the invention to obtainthis shaping in the longitudinal direction by utilizing the particularproperties of the system in question.

It will be quite obvious that the system l5 exerts a deconcentratingeffect on the cathode ray when the mean potential of the plates 8 and 9exceeds the potential of the cathode ray, and that in contradistinctionthereto a concentrating effect, which may be increased up tooverconcentration, may be obtained when the mean potential of theseplates is made negative in relation to the ray.

According to a further object of the invention, the forming of thecross-section of the ray in the longitudinal direction may be obtainedby suitable adjustment of the concentrating effect of this system.

A convenient circuit arrangement is illustrated by way of example inFig. 4. In thesame I5 is the three-plate system with the plates 8, 9 andI0, and 6 the anode. The potentials may be adjusted by means of thepotentiometers 24 and 25.

Assuming it is desired to furnish the image point with the form of anarrow rectangle in the direction of the line, the system, in accordancewith the invention, is to exert a concentrating effect. For this purposethe plates 8 and ID are furnished with a negative potential in relationto the anode, i. e., the ray, whilst the plate 9 in all cases requiresto be connected up with a potential which is positive in relation to theray. It will be observed, however that the pro vision of a stronglynegative potential at the plates Sand I results in an overconcentration,which leads to an intersection of the pencil of cathode rays, and inturn to an increase in the cross-section. An increase in thecross-section may, therefore, be obtained both by making the plates 8and I0 positive in relation to the ray as well as by making the same toostrongly negative in relation to the ray. The most convenient potentialmay readily be determined empirically in the case of every arrangement.It is accordingly possible when employing the method according to theinvention to impart to the image point any desired cross-section.

Naturally, the above considerations with regard to the concentrating ordeconcentrating effect of the deflecting plate systems also apply toordinary two-plate deflecting systems.

An arrangement for shaping the ray with the use of special diaphragms isillustrated by way of example in Fig. 5. In the same 2 is theWehnelt-cylinder having the cathode 3, 4 the preliminary anode, theafter-concentration cylinder and 6 the after-acceleration anode. 26 and28 are the two slotted diaphragms causing the desired forming of theray.

The degree of forming may be varied as desired both by dimensioning ofthe width of slot as well as by selection of the potential applied tothe slotted plate. According to the invention, those potentials mayconveniently be employed which are necessary for the operation of thetube itself. It is possible, for example, to link up the first diaphragmwith the preliminary anode, and the second diaphragm with the middleplate of the three-plate system (which plate possesses a positivepotential in relation to the anode). The desired shaping may then beobtained without difficulty by proper selection of the Width of theslot. In order toavoid variation in the speed of the ray there arepreferably connected between the shaping diaphragms or between shapingdiaphragm and after-connected parts of the system diaphragms whichpossess the potential of the main anode. The apertures of thesediaphragms are so dimensioned that the edges of the diaphragms, owing totheir large spacing away from the ray, exert no or only very littleshaping effect on the same. The length of the slots in the shapingdiaphragms is such that the shaping takes place solely under the efiectof the long bounding faces, and the effect of the narrow faces may beignored. The method according to the invention may naturally also beperformed with the use of magnetic coils.

, It will be understood that the described embodiments are only shown byway of example and that the invention is in no way restricted to them.

It is obvious that the invention may be employed in connection with allkinds of Braun tubes and that it may be employed in connection withvevery kind of deflecting and concentrating means.

The method of the invention enables image points to be produced in anydesired form, and accordingly on the one hand a fully marked screen tobe obtained, and on the other hand an enhanced quality of the image tobe accomplished by diminishing the image element in the direction of theline.

I claim:

1. A Braun tube comprising a cathode and a fluorescent screen, aWehnelt-cylinder surrounding said cathode, an anode plate arrangedbetween said cathode and said fluorescent screen, a further cylinderarranged between said anode plate and said fluorescent screen, a furtheranode arranged between said cylinder and said fluorescent screen, aplate furnished with a rectangular slot arranged between said furtheranode and said fluorescent screen, a screening plate furnished with acentral opening arranged between said slot-plate and said fluorescentscreen,

a further plate furnished with a rectangular slot, said slot beingarranged perpendicularly to the first said slot, said further slot-platearranged between said screening plate and said fluorescent screen, afurther screening plate arranged between said further slot-plate andsaid fluorescent screen, and two three-plate deflecting systems arrangedbetween said further screening plate and. said fluorescent screen, meansto connect the first anode with the first slot-plate, means to connectthe second anode with each of said screening plates, means to connectsaid further slot-plate with the middle plate of the first of saiddeflecting systems, and means to connect all said electrodes with theoperating voltages.

2. A Braun tube comprising an evacuated envelope enclosing a cathode andan anode arranged in operative relationship thereto, means for varyingthe intensity of the ray, said means being arranged between said cathodeand said anode, a fluorescent screen, means for deflecting the ray intwo directions vertical to each other for scanning said fluorescentscreen, and means arranged between said anode and said fluorescentscreen for causing the cross-section of the ray proceeding to saidscreen to assume an exactly defined constant shape other than that whichthe ray possesses when projecting from said anode, said means includingat least one plate having a rectangular slot, two opposite edges of saidslot being arranged in proximity to the path of the ray, the two otheredges of said slot being arranged distant from the path of the ray, saidplate being adapted to be supplied with a constant potential.

3. A Braun tube comprising a cathode, an anode, electrodes forcontrolling the intensity of I the ray, electrodes for concentrating theray, a picture receiving screen, at least one deflecting electrodessystem mounted between said anode and said screen, for applying scanningdeflections to the ray, and at least one electrode incorporated betweenthe deflecting electrodes of at least one of said deflecting electrodessystems to produce electro-static fields for causing the cross-sectionof the ray proceeding to said screen to assume a constant shape otherthan that which the cross-section of the ray possesses when projectingfrom said anode, and means for connecting all of said electrodes withthe respective operating voltages.

KURT SCI-ILESINGER.

